DESCRIPTION: (Verbatim from the Applicant's Abstract) The purpose of this project is to evaluate the contributions of Magnetoencephalography (MEG) to the surgical management of epilepsy. Specifically, we propose the following: First, to estimate the relative accuracy of MEG, as compared to that of surface and invasive electrophysiology, in identifying epileptogenic zones to be resected in patients with focal epilepsy. Second, to explore the possibility that identification of epileptogenic zones based on MEG data combined with data from other standard non-invasive diagnostic procedures and data from the Wada procedure may, in some cases, be sufficiently accurate to obviate the need for invasive electrophysiology. In addition, we propose to examine whether judgements of differential hemispheric involvement in language and memory derived from MEG data concur with those routinely derived from Wada procedure. Finally, incidental to addressing the above main questions, we will also address the question as to whether MEG influences the planning of invasive electrophysiological procedures and we will explore alternative ways of improving its diagnostic accuracy by considering alternative, not yet standardized modes of MEG data collection and analysis.